Modularized respiratory treatment apparatus

ABSTRACT

A modularized respiratory treatment apparatus provides various respiratory pressure treatments. The apparatus may be formed by discrete connectable modules such as a flow generator module, alarm module and/or humidifier module. Each module may include its own external casing or housing to independently retain or enclose the respective components that serve the function of the module. Different modules may be adapted with different components and functionalities and may be readily coupled using standardized gas and electrical connection configurations that have flow and communication paths that extend through the modules. When coupled, operation of the respiratory treatment apparatus may be controlled by detection of different modules, such as the alarm module that generates visual and/or audible alarms based on detected conditions, so as to selectively enable or disable different respiratory treatments. The discrete modules of the medical treatment apparatus may include tamper resistant locking mechanisms to impede unauthorized separation of some modules.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 15/042,335filed on Feb. 12, 2016, which is a divisional of U.S. application Ser.No. 13/608,293 filed on Sep. 10, 2012, now U.S. Pat. No. 9,302,066,which claims the benefit of the filing date of U.S. Provisional PatentApplication No. 61/533,431 filed Sep. 12, 2011, all of which areincorporated herein by reference.

FIELD OF THE TECHNOLOGY

The present technology relates to apparatus for treatment of respiratoryconditions such as pressure treatment apparatus for conditions relatedto obstructive sleep apnea (OSA), central sleep apnea (CSA), sleepdisordered breathing (SDB), Cheyne-Stokes respiration (CSR) allergyinduced upper airway obstruction, early viral infection of the upperairway, respiratory insufficiency etc. More particularly, the technologyinvolves modularization of the components for such respiratory treatmentapparatus.

BACKGROUND OF THE TECHNOLOGY

Sleep is important for good health. Frequent disturbances during sleepor sleep fragmentation can have severe consequences including day-timesleepiness (with the attendant possibility of motor-vehicle accidents),poor mentation, memory problems, depression and hypertension. Forexample, a person with nasal congestion may snore to a point that itdisturbs that person's ability to sleep. Similarly, people with OSA arealso likely to disturb their partner's sleep. One form of treatment forpatients with OSA is continuous positive airway pressure (CPAP) appliedby a flow generator such as a blower (compressor) via a connectingdelivery hose with a patient interface. Such a pressure treatment may beadjusted in response to detected patient conditions such as apneas,snoring or hypopneas but generally maintains an approximately constantpositive pressure during each breathing cycle of the patient. Thepositive pressure can prevent a collapse of the patient's airway duringinspiration, thus preventing events such as snoring, apneas or hypopneasand their sequelae.

Respiratory treatment apparatus may include a flow generator, an airfilter, a patient interface such as a mask or cannula, an air deliveryconduit connecting the flow generator to the mask, various sensors and amicroprocessor-based controller. The flow generator may include aservo-controlled motor and an impeller. The flow generator may alsoinclude a valve capable of discharging air to atmosphere as a means foraltering the pressure delivered to the patient as an alternative tomotor speed control. The sensors may measure, amongst other things,motor speed, gas volumetric flow rate and outlet pressure, such as witha pressure transducer, flow sensor or the like. The apparatus mayoptionally include a humidifier and/or heater elements in the path ofthe air delivery circuit. The controller may include data storagecapacity with or without integrated data retrieval/transfer and displayfunctions.

Positive airway pressure may be delivered in many forms. As previouslymentioned, a CPAP treatment may maintain a treatment pressure across theinspiratory and expiratory levels of the patient's breathing cycle at anapproximately constant level. Alternatively, pressure levels may beadjusted to change synchronously with the patient's breathing cycle. Forexample, pressure may be set at one level during inspiration and anotherlower level during expiration for patient comfort. Such a pressuretreatment system may be referred to as bi-level. Alternatively, thepressure levels may be continuously adjusted to smoothly replicatechanges in the patient's breathing cycle. A pressure setting duringexpiration lower than inspiration may generally be referred to asexpiratory pressure relief. As described by Sullivan in U.S. Pat. No.4,944,310, positive airway pressure treatments typically provide gasunder pressures to the patient in the range of 4 to 15 cmH₂O from thedevice and may involve flow rates of at about 120 liters/minute. Some ofthe air may escape via an end restriction and not be delivered to thepatient. These pressure settings may also be adjusted based on thedetection of conditions of the patient's airway or respiration. Forexample, treatment pressure may be increased in the detection of partialobstruction, apnea or snoring. In some cases, positive airway pressuremay be adapted to provide ventilation support. For example, a patient'sventilatory needs may be supported on a breath-by-breath basis byautomatically calculating a target ventilation and adjusting thepressure support generated by an apparatus, such as a bi-level pressuretreatment apparatus, so as to achieve the target ventilation.

Other devices are known for providing respiratory tract therapy. Forexample, Schroeder et al. describes an apparatus for delivering heatedand humidified air to the respiratory tract of a human patient in U.S.Pat. No. 7,314,046, which was filed on 8 Dec. 2000 and assigned toVapotherm Inc. Similarly, Genger et al. discloses an anti-snoring devicewith a compressor and a nasal air cannula in U.S. Pat. No. 7,080,645,filed 21 Jul. 2003 and assigned to Seleon GmbH.

Respiratory treatment apparatus are sometimes provided with accessorycomponents for comfort conditioning of the flow or pressurized airsupplied by the flow generator. For example, the supplied air may beapplied to a humidifier to humidify and warm the treatment gas prior toits delivery to a patient. Similarly, various heating elements can beconnected with a delivery conduit to help in maintaining a particulartemperature of the supplied gas as it is conducted to the patient from asupply unit or humidifier.

It may be desirable to develop these devices with improved designefficiencies.

SUMMARY OF THE TECHNOLOGY

In an aspect of the present technology, apparatus and methods providerespiratory treatment for a patient.

In another aspect of the present technology, a respiratory treatmentapparatus is formed by separable modules each with its own externalcasing or housing.

Another aspect of one form of the present technology is a systemcomprising a first module that is constructed and arranged to providePositive Airway Pressure (PAP) therapy, and a second module that isconstructed and arranged to provide mitigation in the event of an alarmcondition being fulfilled with respect to the therapy in use. In oneform, the two modules may be physically connected. In one form, thesecond module may be in data communication with the first module,without being physically connected, and nevertheless provide alarmfunctionality.

Another aspect of the present technology is a tamper resistantrespiratory apparatus.

In another aspect of the technology, a respiratory treatment apparatusincludes a separable alarm module, a separable flow generator module anda separable humidifier module. Such a separable design may be, from theperspective of the ordinary user, a permanent attachment or at least anattachment that is difficult for such a user to detach. However, it maybe readily separable by a trained technician for service or replacement.Nevertheless, the design can provide a very easy to attach module thatsimplifies upgrading of a flow generator or other respiratory apparatusso as to add an additional functionality, such as an alarmfunctionality.

Another aspect of the present technology is a system comprisingrespiratory treatment apparatus and a module that is connectable to andremovable from the respiratory treatment apparatus via a latchingmechanism, wherein the latching mechanism has an associated connectionstep and a removing step that is not a reversal of the connection step.Another aspect of the present technology is a process of assembly of amodule to a respiratory apparatus, and a process of removal of themodule from the respiratory apparatus. In one form, the process ofremoval of the module comprises additional or alternative steps to theprocess of assembly of the module.

In some embodiments, the technology involves an alarm module forcoupling with a respiratory treatment apparatus. The respiratorytreatment apparatus may be configured to generate a respiratory pressuretreatment. The alarm module may include a breathable gas flow channel.The channel may include an inlet coupling and outlet coupling such thatthe inlet coupling is adapted to couple with a breathable gas flowoutput of a respiratory treatment apparatus. The alarm module may alsoinclude an alarm component. The module may further include an electricalcoupler that is adapted for electrical communication between the alarmcomponent and a controller of the respiratory treatment apparatus. Thealarm module may also include a modularized housing configured to retainthe channel and the alarm component. The modularized housing may beadapted for removable coupling with a housing of the respiratorytreatment apparatus.

In some embodiments, the apparatus may also include an alarm controllerincluding at least one processor. The processor may be configured foractivating an alarm associated with operation of the respiratorytreatment apparatus. The controller may be retained by the modularizedhousing. In some cases, the alarm module may include a speaker, whereinthe alarm controller is coupled to the speaker and adapted to producethe alarm as an audible sound, and wherein the speaker is retained bythe modularized housing. The alarm module may also include a set oflights, wherein the alarm controller is coupled to the set of lights andconfigured to produce the alarm as a visual warning, and wherein the setof lights is retained by the modularized housing.

One aspect of one form of the present technology is the use of aloudspeaker as an alarm output device.

Another aspect of one form of the present technology is a highefficiency audio driver, preferably a switching mode audio driver,preferably a class D audio amplifier, which may drive the speaker.

Another aspect of one form of the present technology is an electricalsub-system that uses frequency synthesizing to achieve an alarmspectrum.

In some cases, the alarm module may also include a pressure sensor tosense a pressure of the breathable gas of the channel, wherein the alarmcontroller is coupled to the sensor and configured to produce the alarmbased on a signal of the pressure sensor, and wherein the pressuresensor is retained by the modularized housing. The alarm module may alsoinclude a microphone to sense ambient noise, wherein the alarmcontroller is coupled to the microphone and configured to produce thealarm based on a signal of the microphone, and wherein the microphone isretained by the modularized housing.

Optionally, the modularized housing may include a locking mechanism forreleasably locking the modularized housing in a coupling arrangementwith the housing of the respiratory treatment apparatus. The lockingmechanism may include a set of latches. The set of latches may becoupled with a spring. The modularized housing may also include anaccess aperture for releasing the set of latches. The locking mechanismmay also include a securing screw, the securing screw comprising firstand second thread sections, the second thread sections configured forthreaded attachment to a screw hole of the set of latches for retainingthe locking mechanism in a locked arrangement. Optionally, the securingscrew may include an unthreaded shaft portion between the first andsecond threaded sections, the unthreaded shaft portion being configuredto slideably traverse within the screw hole of the set of latches forreleasing the locking mechanism from a locked arrangement. In one form,the securing screw has a double start thread. In another form, thesecuring screw has a three or more start thread.

In some cases, the alarm module may also include a further electricalcoupler, the further coupler adapted for electrical communicationbetween the controller of the respiratory treatment apparatus and acontroller of a humidifier module for the respiratory treatmentapparatus. In some such cases, the alarm module may also include afurther locking mechanism for releasably locking the modularized housingin a coupling arrangement with a housing of a modularized humidificationmodule for the respiratory treatment apparatus. Optionally, the outletcoupling of the alarm module may be adapted for engagement with abreathable gas input to the humidification module. The further lockingmechanism may comprise a set of apertures of the modularized housingconfigured to releasably engage with a set of latches of a housing ofthe modularized humidification module.

Some embodiments of the present technology may involve a system forrespiratory pressure treatment. The system may include a respiratorypressure treatment module having a flow generator, the respiratorypressure treatment module including a controller, with at least oneprocessor, the controller configured to control the flow generator togenerate a pressure treatment to a patient interface according to firstand second pressure therapy regimes, wherein the controller isconfigured to enable the first pressure therapy regime and disable thesecond pressure therapy regime in the absence of a detection by thecontroller of an alarms module. In some cases, the controller of therespiratory pressure treatment module may be configured to enable thesecond pressure therapy regime based on a detection by the controller ofa presence of the alarms module.

Optionally, the alarms module of the system may include a breathable gasflow channel including an inlet coupling and outlet coupling, the inletcoupling adapted to couple with a breathable gas flow output of therespiratory pressure treatment module. It may also include an alarmcontroller having at least one processor, the processor configured foractivating an alarm associated with operation of the respiratorypressure treatment module. The module may also have an electricalcoupler, the coupler adapted for electrical communication between thealarm controller and a controller of the respiratory treatmentapparatus; and a modularized housing configured to retain the channeland the alarm controller, the modularized housing adapted for removablecoupling with a housing of the respiratory pressure treatment module.

In some cases, the first pressure therapy regime may include acontinuous positive airway pressure treatment. The second pressuretherapy regime may include a pressure support ventilation.

Some embodiments of the present technology may involve a method forselectively activating a pressure therapy regime in a pressure treatmentapparatus. The method may be executed by a processor of a flow generatormodule of a pressure treatment apparatus. The method may involvedetecting a presence or absence of a coupled alarms module, the alarmsmodule being adapted for releasable coupling with the flow generatormodule. The method may also involve selecting a pressure therapy regimefrom a plurality of distinct pressure therapy regimes based on thedetection of a presence or absence of the alarms module. The method mayalso involve controlling a generation of a flow of breathable gasaccording to the selected pressure therapy regime. In some cases, afirst pressure therapy regime of the plurality of distinct pressuretherapy regimes may involve a CPAP treatment. The first pressure therapyregime may be selected with processor in the absence of the detection ofthe alarms module. In some such cases, a second pressure therapy regimemay be disabled by the processor in the absence of the detection of thealarms module. Optionally, a second pressure therapy regime of theplurality of distinct pressure therapy regimes comprises bi-levelpressure support ventilation. Optionally, the second pressure therapyregime may be selected with the processor in the presence of thedetection of the alarms module.

Another embodiment of the present technology may involve a tamperresistant locking mechanism for releasably coupling discrete modules ofa treatment apparatus. The locking mechanism may include a movablelatching portion, the movable latching portion being adapted forengagement with engagement apertures of a first housing structure. Itmay also include a securing shaft configured to secure the latchingportion, the securing shaft comprising first and second sets of threadsand an unthreaded shaft portion, the first and second sets of threadsbeing separated by the unthreaded shaft portion.

In some such cases, the latching portion may include a threaded aperturefor the securing shaft. The latching portion may be adapted to besecured against a second housing structure by coupling the second set ofthreads and threaded aperture so as to prevent displacement of thelatching portion from the engagement apertures. Optionally, the threadedaperture of the latching portion may be adapted for slideable engagementwith the unthreaded portion of the securing shaft to permit the latchingportion to be moved for releasing and catching the latching portion. Insome cases, the second housing structure may include a release aperture,the release aperture positioned and sized to selectively permit accessto the latching portion to displace the latching portion for releasingthe latching portion from the engagement apertures.

Optionally, the second housing structure may include a shaft aperturefor receiving the securing shaft and engaging the securing shaft whenthe latching portion is secured against the second housing structurewith the second set of threads of the securing shaft. The lockingmechanism may also include a security label to conceal the shaftaperture. In some cases, the securing shaft may comprise a screw. Also,the first housing structure may include a housing to retain a flowgenerator of a respiratory treatment apparatus and wherein the secondhousing structure comprises a housing to retain an alarms module for therespiratory treatment apparatus.

Further embodiments and features of the present technology will beapparent from the following detailed disclosure, abstract, drawings andthe claims.

BRIEF DESCRIPTION OF DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

FIG. 1 is a schematic diagram of example modules with components of anapparatus for respiratory treatment in some embodiments of the presenttechnology;

FIG. 2 illustrates an embodiment of a modularized respiratory treatmentapparatus having a flow generator module, alarm module and humidifiermodule in a side-by-side coupled arrangement;

FIG. 3 illustrates another embodiment of the modularized respiratorytreatment apparatus having a flow generator module and humidifier modulein a side-by-side coupled arrangement;

FIG. 4 illustrates another embodiment of the modularized respiratorytreatment apparatus having a flow generator module and alarm module in aside-by-side coupled arrangement;

FIG. 5 illustrates another embodiment of the modularized respiratorytreatment apparatus having only a flow generator module;

FIGS. 6A and 6B contain left and right side views that illustrate anembodiment of a modularized alarm module of the present technology;

FIG. 7 is an electronic components schematic of an example arrangementof components of the modularized flow generator, alarm module andhumidifier module in some embodiments of the present technology;

FIGS. 8A and 8B are left and right side isometric projections of anexample embodiment of the modularized alarm module of the presenttechnology;

FIG. 9 is an isometric projection having an exploded view of examplecomponents of the assembly of the modularized alarm module of FIG. 8 ;

FIG. 10 is a three dimensional drawing of some components of a lockingmechanism for a module of a respiratory treatment apparatus of thepresent technology;

FIG. 10A is another view of the components of the locking mechanism ofFIG. 10 ;

FIG. 11 is a cross sectional view of a latching structure of an examplelocking mechanism of the present technology showing the lockingmechanism in secured and engaged position;

FIG. 12 is a cross sectional view of the latching structure of thelocking mechanism of FIG. 11 showing the locking mechanism in unsecured,biased and engaged position;

FIG. 13 is a cross sectional view of the latching structure of thelocking mechanism of FIG. 11 showing the locking mechanism in adisengaged position; and

FIG. 14 is a cross sectional view of the latching structure of thelocking mechanism of FIG. 11 showing the locking mechanism in a engagedposition.

DETAILED DESCRIPTION

Embodiments of the present technology may be useful for implementationas a respiratory treatment apparatus 102 that may be formed by some orall of the modules illustrated in FIGS. 1 to 6 . For example, therespiratory treatment apparatus 102 may be formed by a system ofmodules, each with housings that independently retain the respectivecomponents that serve the function(s) of the individual modules.Desirably, each module may be adapted with different components andfunctionalities and may be easily coupled together depending on thedesired functionality of the respiratory treatment apparatus. Thus, whenso coupled, the operation of the respiratory treatment apparatus 102 maybe dictated based on the presence or absence of the different modulesthat may be detected. The modules may be coupled in a horizontal orside-by-side assembly as illustrated in FIGS. 2-4 . However, otherassembly orientations may be adapted. For example, a vertical orstacking of modules may also be adopted.

In one form of the present technology, a first printed circuit board(PCB) is constructed to provide therapy functionality, for example apressure controller, under the control of a controller that isprogrammed to control delivery of one or more therapeutic regimes.Furthermore, a second, separate PCB is manufactured that is constructedand arranged to provide mitigation actions, for example the signaling ofan alarm condition in the event of a low power situation. In use, whilea module including only the first PCB has the capability of providingcertain therapies, the module will not do so, or will only permit asubset of such therapies, unless a second module containing the secondPCB is in data communication with the first module. The datacommunication may be wireless, but preferably wired.

As illustrated in the example of FIG. 1 , the respiratory treatmentapparatus may include a system formed by one or more of a flow generatormodule 104, an alarm module 106 and/or a humidifier module 108. Eachmodule includes the components for its modularized functionality.Depending on the presence or absence of the alarm module and/orhumidifier module, the flow generator may operate differently.

For example, an alarm module may generally include components andfunctionality for generating different types of alarms associated withthe operations of the flow generator as discussed in more detail herein.The presence of an alarm module, or particular type of alarm module, canthen permit the flow generator to deliver different treatments dependingon its participation in the operation of the apparatus. For example, insome embodiments, without coupling with an alarm module, the flowgenerator may be enabled for certain pressure treatment regimes, such asa CPAP treatment, and not others, such as a pressure support ventilationtreatment, even though the control programming for each of thesedifferent pressure treatment regimes is present in the flow generatormodule. In such a case, certain pressure treatment regimes may bedisabled in the absence of any necessary module such as the alarmmodule. However, when a particular module, such as an alarms module, iscoupled to the system, the flow generator may then be enabled to operatewith the further pressure treatment regimes.

For example, by detecting the alarm module, different pressure treatmentregimes that may be associated with a need for the alarm module may beactivated by a controller of the flow generator. Such a detection andactivation may be fully automated in conjunction with the controllers ofthe flow generator module and alarms module. Alternatively, it may bepartially automated such as by permitting an authorized person to selectand activate a pressure treatment regime when the added module has beendetected by a controller of the flow generator. Similarly, removing ofsuch an alarm module may then disable any pressure therapy regime of theflow generator that may be associated with the removed module. Thus, theflow generator may include programming that serves a safety function topermit enabling or disabling of different pressure treatment regimesdepending on the need for certain functionality of other modules in thecontrol of the particular pressure treatment regime.

Accordingly, in some embodiments, the flow generator module maytypically include a flow generator housing 104H so as to retaincomponents that may be involved in the generation of a pressuretreatment according to one or more pressure treatment regimes. Typicallysuch a module will include a flow generator such as a servo-controlledblower with an air inlet and impeller driven by a motor and aprogrammable controller for controlling the blower. Optionally, the airinlet may be coupled with a gas supply, such as for oxygen, to mix withor supplement the breathable gas supplied by the impeller to the airwayof a user. Moreover, an air filter may be provided, such as a HEPAfilter, to remove dust or other allergens from the air drawn into theair inlet. The flow generator may optionally be configured forgenerating pressure treatment depending on the enabled type of pressuretreatment regime (e.g., continuous level, bi-level, varying level,pressure support etc.) and it may further be adjusted based onrespiratory conditions (e.g., central or obstructive apnea, hypopnea,Cheyne-Stokes breathing, inadequate ventilation, etc.) that may bedetected by the apparatus. Optionally such a module may also include apressure sensor and/or flow sensor for controlling the blower and/ordetecting conditions associated with patient's use of the device.

The controller or processor of the flow generator module 104 istypically configured and adapted to implement the control methodologiessuch as the methods and algorithms described herein. Thus, thecontroller may include integrated chips, a memory and/or processorcontrol instructions or data in an information storage medium. Forexample, programmed instructions encompassing the control methodologymay be coded on integrated chips in the circuits or memory of the deviceor such instructions may be loaded as software or firmware using anappropriate medium. With such a controller or processor, the apparatuscan configured with the different pressure treatment regimes byincluding different pressure delivery equations that are used to set thespeed or pressure of the blower or the exhaust venting by the releasevalve. The controller may enable or disable some treatment regimes basedon the detection of the presence of some module (e.g., an alarm module)that may be required for the particular pressure treatment regime.Similarly, it may enable or disable some treatment regimes based on theabsence of some module. In one form, the controller may be configured tocontrol disabling of all treatment functionality if an alarm module isconnected (e.g., it was detected previously or in a previous session)and then removed (e.g., it is not subsequently again detected). Thiscontrol feature may thus disable functionality that may have beenavailable and operable prior to the detection of the connection of thealarm module.

The flow generator module 104 may also typically be adapted to couplewith a patient interface such as a flow delivery conduit and a mask ornasal prongs or nasal cannula, etc. to carry a flow of air or breathablegas to a patient's airway. In this way it may deliver a pressuretreatment generated by the flow generator.

The flow generator module may couple with the patient interface eitherdirectly or through one or more other modules. To this end, the flowgenerator housing 104H may include a breathable gas output coupling110FG. The outlet or output coupling may be adapted for connection tothe tubing of a patient interface or an inlet or input coupling ofanother module, such as an input gas coupling 112AM of the alarm moduleor the input gas coupling 112HM of a humidifier housing 108H ofhumidifier module 108. Similarly, each module may have an outlet oroutput breathable gas coupling such as breathable gas output coupling110AM of the alarm module and output coupling 110HM of the humidifiermodule. In this way, a breathable gas channel (illustrated in FIG. 1 asline “GC”) from the flow generator may be formed by and extend throughone or more modules to the patient interface from the flow generatormodule.

Optionally, a module of the system, such as the flow generator modulemay couple to a further sensor module such as a pulse oximeter module.For example, the pulse oximeter module may have a housing that attachesto the housing of the flow generator module. The pulse oximeter mayoptionally measure blood gas, such as with a finger sensor. The pulseoximeter module then may be configured to communicate information withthe flow generator module, such as detected blood gas data or otherconditions associated with a pulse oximeter.

Accordingly, the modules of the system may also have one or moreelectrical coupler(s) 114 for coupling the modules together fordistributing power, such as from a shared power supply, and/or forcommunications between the modules of the system. Thus, the coupler mayinclude one or more wires to a bus such as the bus described in U.S.patent application Ser. No. 13/060,566 and PCT/AU2009/001168, the entiredisclosures of which are incorporated herein by reference. In suchembodiments, the modules may each have a signal interface for aprocessor of the module for receiving and transmitting signals on thebus.

Thus, as illustrated in FIG. 1 , a module, such as the alarm module, mayhave multiple couplers to permit a common bus to be expanded through oneor more modules. In this regard, communication signals from or to anouter module, such as the humidifier, may pass through other modules,such as the alarm module, to permit communication with a base module,such as the flow generator. For example in some embodiments of such asystem, the flow generator module may communicate through the alarmmodule to the humidifier module. Optionally, in some embodiments of sucha system, the flow generator module may communicate through thehumidifier module to the alarm module. Communications through additionalmodules may also be implemented.

The structure of each module's housing can provide a basis forstandardizing an attachment configuration for self-alignment of theelectrical and gas flow connections of the modules. In this regard, theconnections may be structured as a portion of each housing, and may doso without flexible hoses or cables, to permit a simplified attachmentof each connection. For example, with such self-aligning connections, byaligning the housings of two modules for connection, this may also serveto align the couplings and couplers for attachment. Thus, when thehousings are aligned for connection, the flow couplings and theelectrical couplers are thereby aligned so as to permit them both to beconnected to their respective ports on each module simply by pushing themodules together. In such a case, it would not be necessary toseparately connect the gas channel couplings and the electricalcouplers. By keeping such a uniform connection structure (e.g., thedistances between the gas connections and the electrical connections,their size and positioning on the housing) across different types ofmodules, it can simplify the use of different types of modules with abase module that may be the flow generator.

In this regard, and as illustrated in FIG. 1 , the distance between theinput connections (e.g., the gas connection and the electricalconnection) as well as their size and positioning on both the alarmmodule and the humidifier module may be the same for each module topermit either to be connected directly to the flow generator when it isserving as the base module. Similarly, the distance between the outputconnections (e.g., the gas connection and the electrical connections) aswell as their size and positioning on both the alarm module and the flowgenerator module may be the same for each module to permit theconnections. Such a complementary structural design between thedifferent modules can more easily permit the implementation of astandard flow generator module that can optionally serve with differentadditional modules to become different types of respiratory treatmentapparatus that provide different treatments depending on the presence ofthe modules.

Optionally, the housing structures of the modules of the system may alsoinclude one or more connection components to serve as a lockingmechanism 116 that retains at least two modules together for operationwhen they are connected. For example, some embodiments may employ a setof one or more latches 116L and keepers 116K as discussed in more detailherein. The locking mechanism 116 is adapted as a portion of thestructure of the housings of the modules so that when the lockingmechanism 116 of two modules is aligned to engage for retaining thehousings of the modules together, the gas couplings between the modulesand the electrical couplers between the modules will be in theappropriate coupled position for operation.

In some cases, these locking mechanism components may be designed to bereleasable so as to allow simple attachment and separation. However,they may also be designed so as to inhibit separation once they areattached. For example, they may be designed to prevent or impede certainusers or patients from releasing the locking mechanism and separatingthe housings of the modules but permit others, such as physicians ormanufacturing and maintenance personnel, to release and separate thehousings.

Example Alarm Module Embodiment

An example embodiment of an alarm module of the system may be furtherconsidered in reference to FIGS. 7 through 9 . As schematically shown inFIG. 7 , the alarm module may include several components that assistwith generating alarm signals associated with the operation of a flowgenerator to which the module may be attached. As shown, the alarmmodule may include visual indicators, such as an LED or LCD, forconveying status or warning information to a user. For example, themodule may optionally have an alarm display 769, such as an LCD, topresent text warning messages to a user to describe a detected alarmcondition and/or how to resolve or address the alarm condition.Similarly, and by way of further example, the module may also oralternatively have status lights 770 and warning lights 772. The statuslight may provide an indication that the alarm module is operating andfunctioning properly. The warning lights 772 may include a light toindicate that a treatment therapy is active or not active. The warninglights may further include an alarm light to indicate that a low and/ormedium priority alarm has been triggered or not. The warning lights mayalso include an alarm light to indicate that a high priority alarm hasbeen triggered or not. Optionally, to audibly convey a warning, themodule may also include an audible indicator such as a loudspeaker 774.

One or more sensors 776 may also be provided in the alarm module fordetecting a condition associated with a provided treatment. For example,the sensors may include a pressure sensor and/or a flow sensor (e.g.,differential pressure sensor) to detect pressure and/or flow conditionsin the gas channel GC of the alarm module. Optionally, a pressure sensormay be provided to sense ambient pressure or the pressure outside of thegas channel. Such a sensor may provide an ambient pressure signal topermit the alarm module or another module to determine or estimatealtitude of the system or alarm module. The estimate of altitude maythen be used in the control of the system, such as the setting oftreatment pressure by the flow generator module. Optionally, such asensor may generate a warning if a detected ambient pressure or altitudeis not appropriate for use of the respiratory treatment apparatus.

Optionally, the sensors of the alarm module may also include amicrophone to sense ambient sound or noise. For example, by sensingambient sound or noise in the environment in which the alarm module isbeing utilized, the alarm module may be used for a process that sets asuitable sound level of an alarm. For example, by detecting a higheramplitude noise level in the environment in an ambient sound testingprocedure with the sound sensor, a processor of the module or anothermodule may automatically set a higher alarm output volume settingassociated with a speaker of the alarm module. When a quieterenvironment is detected, a lower setting may be automatically set in thealarm module. For example, a selected output level for the alarm speakermay be selected by the module that is a certain threshold level abovethe sensed ambient sound/noise level. Such a volume setting process maybe executed when the alarm module is initially powered for operation,periodically (e.g., every thirty minutes) during use of the system or ina just-in-time process that is executed by the module immediately beforeactivation of an audible alarm but after an alarm condition has beendetected.

The ambient sound sensor may also be utilized in a speaker/alarmself-testing process. For example, a processor may control activation ofan audible test alarm sound through a speaker of the alarm, such as whenthe alarm module is initially powered. The sound sensor may then detectwhether or not the alarm sounded through the speaker by sensing thealarm sound with the sound sensor. For example, an alarm tone at a knownfrequency may be played through the speaker and the sound sensor wouldgenerate a signal from the ambient noise of the environment includingthe sound of the alarm tone, which may be accessed as data by aprocessor. The processor may then detect whether or not the knownfrequency exists within the data of the signal from the sound sensorand/or whether or not the amplitude component at the detected frequencyis at a suitable level. The existence of the tone and/or the existenceof the tone at a sufficient magnitude would indicate that the alarmspeaker is functioning. If the tone is not located in the signal by theprocessor or if the detected frequency does not have a sufficientmagnitude, a warning may be activated by the alarm device such as awritten message or a warning light. The warning may indicate that thespeaker is not operating or the speaker is not operating loudly enough.Optionally, the self testing process may be conducted during use of theapparatus in response to the generation of an alarm condition as a testto ensure the alarm is sounding. Failure to sense the audible alarm mayresult in an alternative warning and/or shutting down the apparatus.

In some embodiments, a microcontroller 778, such as a processor, mayalso be included in the alarm module to control the operation of theaudible indicators, the visual indicators, and/or to receive signalsfrom the sensors via one or more interfaces 780. The microcontroller 778may also be coupled to a bus 782 for the system as previously discussedvia a bus interface 784 for communication with other modules such assending messages and receiving messages to the other modules, such asthe flow generator module, concerning status of alarm conditions orstatus of the alarm module. Optionally, the microcontroller 778 maymonitor power with a power detector 786 coupled with the bus 782. In theevent that power supplied from the bus, such as from a power sourceassociated with the flow generator module 104 is not sufficient asdetected by the power detector 786, the components of the module may besupplied with power from an optional back power source 788 such as oneor more rechargeable batteries or supercapacitors.

The alarm module may also include a user input interface 790 for usercontrol associated with the alarms. For example, the user inputinterface 790 may include a mute button 792 to silence an audible alarm.It may also optionally include a reset to reset an alarm. The inputinterface may also be implemented to set or configure the conditionsassociated with the alarms of the alarm module as discussed in moredetail herein.

Example Alarm Module Control Methodologies

Generally, the alarm module with and/or without the flow generatormodule may be considered an intelligent alarm system. As such, thecontroller of the alarm module, either independently or depending on theadditional control of another module, such as the microcontroller 796 ofthe flow generator module 104, will execute processing to determine thepresence or absence of an alarm condition associated with therespiratory treatment apparatus and the priority of the alarm.

Thus, in some embodiments, the microcontroller 778 of the alarm modulemay execute prioritized alarm indications, visible and audible, and maydetect alarm conditions under the control of another microcontroller ofa different module, such as the controller of the flow generator whichacts as a master or main controller. However, the microcontroller 778 ofthe alarm module may independently detect the alarm conditions andactivate audio and visual alarms as well as generate signals to othermodules concerning the presence and nature of the alarm. For example, apower fail condition may be detected and an associated alarm conditionmay be initiated by the alarm module microcontroller independently ofother module's controller(s). The detection of such a condition mayresult in an audible and visual alarm being generated by the alarmmodule 106 and a signal being sent to the controller of other modulesconcerning the condition.

In some cases, the alarms generated by the controller of the alarmmodule may involve latching alarm signals that activate the audibleand/or visual alarm indicators. A latching alarm signal is one thatcontinues to be generated after its triggering event is no longerdetected and may be stopped by a deliberate user action, such as thepressing of a reset button. However, some alarm signals once activatedmay not be easily deactivated. In such a case, some alarms may not bereset by a user. Moreover, in some embodiments, the processing of thecontroller(s) may be configured to permit some of the alarms conditionsto be selectable or modifiable by a user or authorized clinician whilesome of the alarm conditions may be fixed so as to prevent disablement.

Example alarms that may be activated and/or detected with the alarmmodule may include a power fail condition, a high pressure or overpressure condition, a system fault (e.g., an over temperature condition,a blocked tube of a patient interface or blocked gas channel,disconnected patient interface or tube thereof, a humidifier lid open, ahigh leak or Mask Off condition), a non-vented mask condition, a Lowpressure settable condition, a high pressure settable condition, a lowminute ventilation condition, a apnea condition and/or a sensor failurecondition, etc. Whether detected by the alarm module or controller ofanother module, the controller of the alarm module will generate theaudible and/or visual alarms associated with these conditions in thealarm module with the visual and/or audible indicators of the alarmmodule. In the case that the condition is detected by the controller ofanother module, the detecting module will transmit a signal on the busto the alarm module. When the controller of the alarm module receivesthe signal, the controller of the alarm module will then generate theappropriate audible and/or visual alarms based on the type of alarmmessage received on the bus.

Additional example conditions that may be assessed by one or morecontrollers for detecting the above listed alarms may be as follows:

(1) a power fail condition: no power or insufficient power is detectedwhile the flow generator is delivering a pressure treatment.

(2) a high pressure or over pressure condition: a sensed pressure isgreater than a pressure threshold (e.g., 25 or 30 depending on thedetected type of flow generated module attached) for a time periodexceeding a time threshold (e.g., 0.7 seconds).

(3) an over temperature condition: a temperature detected by athermister associated with a controller of any attached module hasexceeded a temperature threshold.

(4) a blocked tube of a patient interface or blocked gas channel: ameasure of patient flow is below a flow threshold (e.g., 12 liters perminute) and a measure of pressure is above a pressure threshold (e.g.,10 cmH₂O) for a period of time exceeding a time threshold (e.g., in arange of about 30 to 50 seconds, such as 40 seconds).

(5) a disconnected patient interface or tube thereof: this condition maybe detected when a measure of pressure is less than a pressure threshold(e.g., 2 cmH₂O) and a measure of blower speed is above a speed threshold(e.g., 8955 revolutions per minute) for a period of time exceeding atime threshold (e.g., 1 second).

(6) a humidifier lid open: the presence of the humidifier module isdetected and a lid sensor is detected as being open or a measure ofpressure is detected below a pressure threshold (e.g., 3.5 cmH₂O) and ameasure of flow is detected as being over a flow threshold (e.g., 120liters per minute) for a time exceeding a time threshold (e.g., 5seconds).

(7) a high leak or Mask Off condition: a measure of leak exceeds a leakthreshold (e.g., 40 liters/minute) for a time period exceeding a timethreshold (e.g., 20 seconds). A controller may deactivate this alarmwhen the measure of leak falls below the leak threshold for a period oftime (e.g., 6 seconds.)

(8) a non-vented mask condition: this condition may be detected whenflow generator is determined to be generating a pressure treatment for anon-vented mask and a measure of leak falls below a leak threshold(e.g., −7.5 liters per minute) for a period of time that exceeds a timethreshold (e.g., 10 seconds). A controller may deactivate this alarmwhen the measure of leak is above a leak threshold (e.g., 7.5 liters perminute) for a period of time (e.g., 30 seconds.)

(9) a Low pressure settable condition: this condition may be detectedwhen a measure of pressure is less than a pressure treatment setting bysome user-configured amount (e.g., 0 to 10 cmH₂O) for a period of timeexceeding a time threshold (e.g., 12 seconds). A controller maydeactivate this alarm when the measure of pressure satisfies thepressure treatment setting for a period exceeding a time threshold(e.g., 100 milliseconds).

(10) a high pressure settable condition: this condition may be detectedwhen a measure of pressure is higher than a pressure treatment settingby some user-configured margin (e.g., 0 or 4 to 35 cmH₂O) for a periodof time exceeding a time threshold (e.g., 7 seconds). A controller maydeactivate this alarm when the measure of pressure satisfies thepressure treatment setting for a period exceeding a time threshold(e.g., 100 milliseconds).

(11) a low ventilation condition: this condition may be detected when ameasure of ventilation (e.g., a minute ventilation) falls below aconfigurable ventilation threshold (e.g., 1 to 20 liters per minute). Acontroller may deactivate this alarm when the measure of ventilationsatisfies the ventilation threshold for a period of time exceeding atime threshold (e.g., 30 seconds).

(12) an apnea condition: this condition may be detected when there areno breaths detected within a time period exceeding a configurable timethreshold (e.g., 5 to 45 seconds). A controller may deactivate thisalarm when a number of spontaneous breaths (e.g., 3) are detected in thetime period.

(13) a sensor failure condition (e.g., pressure transducer): thiscondition may be detected if the flow generator module is generating apressure treatment (e.g., is in run mode) and if a measure of pressureis less then a pressure threshold (e.g., 1 cmH₂O) for over a period oftime exceeding a time threshold (e.g., 5 seconds). Other alarmconditions may also be implemented.

(14) Oximeter Sensor Failure: this condition may be detected if a flowgenerator module fails to detect a connection to an oximeter module whenthe flow generator treatment mode is configured to use an oximeter. Thedetection of the absence of the oximeter may result in activation of analarm through the alarm module such as a message on an LCD, a warninglight or LED and/or an audible warning sound via a sound generator(e.g., a warning tone or an audible voice message advising a user toconnect an oximeter).

(15) Oximeter Dislodged Condition: This condition may be detected if anoximeter module detects that an oximeter finger sensor has fallen off apatient's finger. For example, a pulse oximeter module may detect thedislodged sensor and send a message to an alarms module via a flowgenerator module. The detection of the dislodged sensor may result inactivation of an alarm of the alarm module such as a message on an LCD,a warning light or LED and/or an audible warning sound via a soundgenerator (e.g., a warning tone or an audible voice message advising auser to wear the sensor).

(16) Blood Gas Condition: This condition may be detected if a measuredblood gas, such as a blood gas measured by an oximeter module, does notmeet a threshold. For example, if a low oxygen level is detected, suchas if PaO₂ falls below a percentage threshold (e.g., 85%). The detectionof the dislodged sensor may result in activation of an alarm of thealarm module, such as in response to a communication from the flowgenerator module. The alarm activated in the alarm module may be amessage on an LCD, a warning light or LED and/or an audible warningsound via a sound generator (e.g., a warning tone or an audible voicemessage advising a user of a low blood gas condition).

(17) A Back-up Power Source Warning: This condition may be detected ifthe back-up power source of the module does not meet requiredperformance requirements such as holding sufficient power for back-upoperations. For example, in the case of a supercapacitor, themicrocontroller may generate an early warning signal by detecting adecrease in the capacitance of the supercapacitor. In such a case, themicrocontroller of the alarms module may monitor the charging and/ordischarging rate of the supercapacitor during main power on/off anddetermine the approximate capacitance of the supercapacitors. An alarmmay be generated if the determined capacitance does not meet apredetermined threshold. Other methods for testing the back-up power mayalso be implemented and may depend on the type of back-up source. Thealarm activated in the alarm module may be a message on an LCD, awarning light or LED and/or an audible warning sound via a soundgenerator (e.g., a warning tone or an audible voice message advising auser to seek service of the back-up power source.)

The following Table A identifies whether some of the previouslydescribed alarm conditions have settings (e.g., configurable thresholdsfor the conditions and/or whether the alarm conditions may beenabled/disabled) that may be adjusted or configured by a user and/orclinician and whether the alarms may be reset once they have beentriggered for an example embodiment.

TABLE A Alarm Configurable Resetable Power Fail N N Over Pressure N NSystem Fault N N Over temperature N N Blocked tube N N Humidifier lidopen N N High Leak/Mask Off Y Y Non-Vented Mask Y Y Low Pressuresettable Y Y High Pressure settable Y Y Low minute Ventilation Y Y ApneaY Y Sensor Failure N N

Example Alarm Sound Signal

One aspect of one form of the present technology is an alarm that usesfrequency synthesizing to achieve the alarm spectrum. One example of analarm sound signal is to use a microcontroller to synthesize a complexfrequency signal that contains a fundamental frequency and four harmonicsound frequencies. A digital to analog converter (DAC) may then be usedto produce the required sound signal. An example methodology forproducing the sound signal is as follows:

-   1. Choose a fundamental frequency F₀; let ω₀=2πF₀;-   2. Compose a sound signal:    S(t)=k1 sin(ω₀ t+ϕ ₁)+k2 sin(2ω₀ t+ϕ ₂)+k3 sin(3ω₀ t+ϕ ₃)+k4 sin(4ω₀    t+ϕ ₄)+k5 sin(ω₀ t+ϕ ₅)    -   where:

k1 . . . k5 are the amplitude coefficients that will be used to finetune the sound pressure level of the harmonics;

ϕ₁ . . . ϕ₅ are the initial phase shift for individual frequencycomponents. The defaults of the amplitude coefficients may be set to 1;the default phase shifts may be set to 0°. These coefficients can betuned as desired.

-   3. Sample the sound signal S(t) at a rate of SR=32X5F₀ for a period    of T=1/F₀; start from t=0;-   4. Convert the sampled data, such as to an 8-bit DAC dataset for a    digital to analog converter of the microcontroller of the alarm    module:

${{DATA}(n)} = {{128} + \frac{250 \times {S\left( t_{n} \right)}}{{{Max}\left( {S(t)} \right)} - {{Min}\left( {S(t)} \right)}}}$

In one form of the present technology, an alarm speaker is driven by aswitching mode audio driver, for example, a class D amplifier (PWMmodulated by synthesized signal). An advantage of this approach is thatit is a high efficiency amplifier, for example with an electricalefficiency of 90% or greater. By way of comparison, a class C linearamplifier may have an electrical efficiency of less than 50%. This highefficiency amplifier does not need additional storage capacitor andprovides a very wide output volume adjustment range.

Example Alarm Module Structure

The modularized housing structure of the alarm module may be consideredin more detail in reference to FIGS. 8A, 8B and 9 . In this embodiment,the components of the alarm module housing 106H include an upper case806, a lower case 808 and a housing support 810. The upper case 806serves as a panel for the mute button 792 and may also include a panelwhich may be for a label for the mute button or may optionally be for anLCD-type alarm display 769 in some embodiments. The lower case 808serves as a base for the alarm module and may include a window 812 forwarning lights 772.

The housing support 810, to which the lower case and upper case of thehousing may be attached, contains an electronics board 914 for thepreviously described electronics components of the module (e.g., themicrocontroller, bus, sensors, lights, interface for speaker 816 etc.).For example, a sensor coupling 773 may be included for coupling of apressure sensor to a gas channel of the module. In such a case thecoupling may be connected with a pressure sensor attached to theelectronics board 914 and the coupling permits the pressure sensor toseal with the gas channel for sensing pressure in the gas channel. Thehousing support 810 is also formed so as to include the gas channel GC.The gas couplings (e.g., input coupling 112AM) may attach to the gaschannel GC of the housing support 810 such as by an interference fit ormay be formed as part of the housing support such as in the case of theoutput coupling 110AM. Similarly, the electrical coupler 114 is attachedto the housing support 810 and wired to the electronics board 914 whichincludes wiring for the bus. The electrical coupler may be either a maleplug or female receptacle version. In the version of FIG. 8A, a maleplug of the alarm module may be inserted into a female receptacle of theflow generator module. Optionally, the alarm module may include anelectrical coupler of the female receptacle version (shown in FIG. 8B)on the opposing side of the alarm module into which a male plug of thehumidifier module may be inserted.

A latching element 918 of the locking mechanism 116 including latches116L is attached to the housing support 810 with latch retainer 920 andretainer screws 924 so as to hold the latching element 918 against thehousing support 810 but permit the latching element to traverselaterally under the retainer for a latching movement. The latch retainer920 includes latch slots 921 in which the latches may move. The lateralmovement of the latching element, and particularly the latches 116L,permits the latches 116L to move to an engagement position EP anddisengagement position DP to engage or disengage with engagementapertures or keepers 116K of another module structure (e.g., a flowgenerator module) to which the alarm module may be attached.

A securing shaft 926 is provided for selectably securing and releasingthe latching element 918 to permit or prevent its lateral movement underthe retainer in a direction indicated by line AA of FIG. 9 . Asillustrated in more detail in FIGS. 10 and 10A, the securing shaft 926,which may for example include a screw head or bolt head, may includemultiple threaded portions, such as first threaded portion 1028 andsecond threaded portion 1030 separated by a blank or unthreaded shaftportion 1032. In an alternative form, securing shaft 926 may have asingle threaded portion. The threaded portions are sized for a threadedaperture 1034 integrated with the latching element 918. When assembled,the securing shaft 926 may be inserted within or through a housingaperture 1036, which may be unthreaded, of the alarm module housing 106Hor housing support 810 to engage with the threaded aperture 1034 of thelatching element. A biasing element 1038, such as a spring, may beprovided to bias the latching element to a particular position along itslateral movement path. For example, as discussed in more detail withregard to FIG. 12 , the biasing element may bias the latching elementsuch that the latches will automatically engage in a locked positionwhen inserted or engaged with the engagement apertures or keepers 116Kof another module. When a spring is implemented, the latching element918 may include a spring mount 1049 for attaching the spring to thelatching element 918.

The components of the locking mechanism can provide a tamper resistantmeans for releasably locking two modules together, such as the alarmsmodule and the flow generator module of a respiratory treatmentapparatus. The tamper resistant operation of the locking mechanism maybe considered in reference to FIGS. 11 through 14 . In FIG. 11 , thesecond threaded portion 1030 is engaged with the threaded aperture 1034of the latching element 918 so as to secure the latching element frommovement such as by retaining it against a portion of the housingsupport 810. In this position, the latching element 918 is locked frommovement as the shaft end 1102 of the securing shaft 926 plies against ashaft stop 1104 of the housing support 810 to force the latching element918 against the housing support 810 when the securing shaft is threadedinto the latching element 918. Thus, the latches 116L of the latchingelement will remain engaged with the keepers 116K or engagementapertures of another module in which they have been inserted and preventthe module from being separated. Optionally, the housing support 810 mayinclude a raised aperture ridge 1140 surrounding the housing aperture1036. The aperture ridge 1140 may conceal the head of the securing shaft926 below the ridge when the securing shaft locks the latching element.In such a case, an optional security label 1150 or sticker may beapplied or adhered to the housing support over the aperture ridge 1140and the securing shaft 926 that is positioned beneath the ridge.Tampering with or removal of the label 1150 may serve as an indicationof unauthorized access to the securing shaft 926 and unauthorizedseparation of the modules locked by the locking mechanism.

In FIG. 12 , the locking mechanism remains locked due to the bias of thebiasing element 1038 (not shown in FIG. 12 ) which may provide a biasingforce BF to bias the latching element 918 against the housing support810 even when the securing shaft has been unthreaded from the threadedaperture 1034 of the latching element 918. In this biased position, thelatches 116L are still in the engaged position EP with respect to anyengagement aperture or keeper 116K of another module. Due to thestructure of the alarm module housing 106H, when the module is attachedto another module, the latching element or latches are not readilyaccessible to move the latching element 918 into its disengagementposition DP.

In this regard, the alarm module housing 106H protects against orconceals access to the latching element 918 and may provide only limitedaccess to it. For example, a small release port 1330, such as a pin holethat may be covered by the label 1150, may be provided to access andmove the latching element 918 when it is unthreaded from the securingshaft as illustrated in FIG. 13 . The latching element overlaps therelease port 1330 such as at an optional tail portion 1332 of thelatching element 918. When applying a rigid wire or pin 1344 sized topass through the release port 1330, the wire or pin can ply against thelatching element, such as at the tail portion 1332, to counteract thebiasing force and laterally move the latching element to itsdisengagement position DP. This lateral movement is permitted becausethe unthreaded shaft portion 1032 does not restrict lateral movement ofthe latching element. In other words, the threaded aperture 1034 of thelatching element 918 can traverse along the unthreaded shaft portion1032, and may do so without rotation of the shaft portion due to thesmaller diameter of the unthreaded shaft portion relative to the firstand second threaded portions and the threaded aperture 1034, in order tomove between the engaged position and the disengaged position. Due tothe biasing force provided by the biasing element 1038 of the latchingelement 918, when the pin or wire is removed, the latching element 918will return to its engaged position.

As shown in FIG. 14 , the particular location of the shaft stop 1102 andsize of the threaded portions and securing shaft 926, allows thesecuring shaft to be tightened into the threads of the threaded apertureof the latching element when the securing shaft is pressed inwardstoward the latching element 918 because the biasing force of the biasingelement pushes the latching element against the second threaded portion1030. However, it does not allow a pressing against the securing shaft926 to move the latching element 918 into its disengaged position fromits engaged position even when the securing shaft 926 is unthreaded fromthe latching element 918. In this regard, the distance which thesecuring shaft 926 may be pressed inward toward the shaft stop 1102 isnot sufficient for the end of the second threaded portion 1030 to pushthe latching element to its disengaged position DP.

In the foregoing description and in the accompanying drawings, specificterminology, equations and drawing symbols are set forth to provide athorough understanding of the present technology. In some instances, theterminology and symbols may imply specific details that are not requiredto practice the technology. For example, although the terms “first” and“second” have been used, unless otherwise specified, they are notintended to indicate any order but may be utilized to distinguishbetween distinct elements. Moreover, although the technology herein hasbeen described with reference to particular embodiments, it is to beunderstood that these embodiments are merely illustrative of theprinciples and applications of the technology. It is therefore to beunderstood that numerous modifications may be made to the illustrativeembodiments and that other arrangements may be devised without departingfrom the spirit and scope of the technology. For example, as previouslydiscussed, in some embodiments the components within the housing of thealarm module may include a controller with a processor to control alarmswith alarm components (e.g., speaker, lights, LEDs, LCD etc.) thatproduce warning and alarms in the alarm module. However, in someembodiments, such a controller or processor may be in other modules,such as the flow generator module. In such a case, the alarm module neednot include a controller but may include the alarm components thatelectronically couple to a controller of another module.

Moreover, while the illustrated alarms module includes a housing thatserves as an external casing to retain the components of the module, insome embodiments the alarm components of the module may be configured asan alarms card that may be inserted within another module, such asinside the housing of the flow generator module. In such a case, thealarms card may include the aforementioned components and functions ofthe alarms module. However, the card may be docked with electrical andgas connections on a mother board within the housing of the flowgenerator, such as if the housing of the flow generator is configured toopen and close. In such a case, the housing of the flow generator modulecan serve as an external casing for the alarms card as well as the flowgenerator. Such an alarms card may or may not have an independenthousing of its own.

Still further, and as contemplated and previously described herein, themodules may be coupled together with certain tamper resistant lockingfeatures as described in more detail herein. Thus, modules of anyfunctionality may be coupled together with such features. For example,in addition to being integrated with an alarms module or a flowgenerator module, the tamper resistant locking features may beimplemented with one or more modules such as a wired and/or wirelesscommunications module that permits electronic data and instructions tobe transferred to and from the system or flow generator such as vianetwork communications. For example, a person may “daisy chain” one ormore additional modules to a respiratory treatment apparatus. Othermodule examples include a docking interface module, such as one thatpermits easy electronic docking of other user devices to the respiratorysystem so that they may operate and communicate with the system (e.g., amusic player dock, a LCD display dock, a smart phone dock, an electronicpersonal data assistant dock etc.).

In an alternative configuration, the one or more modules may beconnected to the top, bottom, front or back of the respiratory treatmentapparatus, or any combination thereof. In an alternative configuration,the one or more modules may be connected to an interior portion of therespiratory treatment apparatus.

One of the advantages of one form of the present technology, where thereare separate therapy and mitigation modules, is a reduced productdevelopment time. Another advantage of one form of the presenttechnology, where there are separate therapy and mitigation modules, isimproved manufacturing efficiencies.

Despite the complexity of a speaker when compared to a buzzer, and themore complicated manufacture procedure for including a speaker,implementation of a speaker is preferred in the present technology. Anadvantage of the use of a speaker in accordance with the presenttechnology is the improved electrical efficiency, which can lead toreduced power requirements and reduced physical size of a correspondingsupercapacitor.

A further advantage of one form of the present technology is that itimproves the safety of a respiratory apparatus by making it difficultfor a patient to inadvertently remove a safety feature, e.g. an alarmmodule, in those situations where it may be important for such anadditional module to remain connected once it has been added to therespiratory treatment apparatus.

Reference signs list Part References Numbers respiratory treatmentapparatus 102 flow generator module 104 flow generator housing    104Halarm module 106 alarm module housing    106H humidifier module 108humidifier housing    108H output coupling    110AM breathable gasoutput coupling   110FG electrical coupler 114 locking mechanism 116keepers    116K latches    116L alarm display 769 status lights 770warning lights 772 sensor coupling 773 loudspeaker 774 sensors 776microcontroller 778 interfaces 780 bus 782 bus interface 784 powerdetector 786 optional back power source 788 user input interface 790mute button 792 upper case 806 case 808 housing support 810 window 812speaker 816 electronics board 914 latching element 918 latch retainer920 latch slots 921 retainer screws 924 shaft 926 threaded portion 1028 threaded portion 1030  unthreaded shaft portion 1032  aperture 1034 housing aperture 1036  biasing element 1038  spring mount 1049  shaftstop 1102  aperture ridge 1140  label 1150  release port 1330  smallrelease port 1330  tail portion 1332  pin 1344 

The invention claimed is:
 1. A tamper resistant locking mechanism forreleasably coupling discrete modules of a treatment apparatus, thelocking mechanism comprising: a movable latching portion, the movablelatching portion being adapted for engagement with engagement aperturesof a first housing structure; and a securing shaft configured to securethe latching portion, the securing shaft comprising first and secondsets of threads and an unthreaded shaft portion, the first and secondsets of threads being separated by the unthreaded shaft portion.
 2. Thelocking mechanism of claim 1 wherein the latching portion comprises athreaded aperture for the securing shaft, the latching portion adaptedto be secured against a second housing structure by coupling the secondset of threads and threaded aperture so as to prevent displacement ofthe latching portion from the engagement apertures.
 3. The lockingmechanism of claim 2 wherein the threaded aperture of the latchingportion is adapted for slideable engagement with the unthreaded portionof the securing shaft to permit the latching portion to be moved forreleasing and catching the latching portion.
 4. The locking mechanism ofclaim 2 wherein the second housing structure comprises a releaseaperture, the release aperture positioned and sized to selectivelypermit access to the latching portion to displace the latching portionfor releasing the latching portion from the engagement apertures.
 5. Thelocking mechanism of claim 2 wherein the second housing structurecomprises an shaft aperture for receiving the securing shaft andengaging the securing shaft when the latching portion is secured againstthe second housing structure with the second set of threads of thesecuring shaft.
 6. The locking mechanism of claim 5 further comprising asecurity label to conceal the shaft aperture.
 7. The locking mechanismof claim 6 wherein the securing shaft comprises a screw.
 8. The lockingmechanism of claim 2 wherein the first housing structure comprises ahousing to retain a flow generator of a respiratory treatment apparatusand wherein the second housing structure comprises a housing to retainan alarms module for the respiratory treatment apparatus.